A. Field of the Invention
The present invention relates broadly to linear light forms and, more specifically, to linear light forms for use in side lighting applications, more specifically, functional lighting applications and/or decorative lighting applications. Furthermore the present invention relates to manufacturing processes for a linear light form that reduces the cost of manufacture and increases the throughput of the light form.
B. Discussion of the Prior Art
Fiber optic light conduits, which are a type of linear light form, are described in U.S. Patents, for example, U.S. Pat. Nos. 5,333,228, 4,933,815, 4,763,984, and 5,067,831 in which the fiber optic light conduit includes generally a fiber-optic core and a cladding material. The addition of a jacketing material extruded over the fiber-optic core and cladding material has been desirable in applications that: require the fiber-optic core and cladding to be protected from the environment and/or require an encasement for multiple strands, each comprised of fiber optic core and cladding material.
When used in functional and/or decorative lighting applications, linear light forms comprising a thermoset core composition are presently preferred due to the outstanding light transmission efficiency, environmental capabilities, mechanical properties and ease of use qualities. Thermoset cores are desirable for such applications because such cores can be produced in a solid form and with a single strand of core material.
Nonetheless, while suited for their intended purpose, thermoset cores with a cladding do not produce auras similar to neon lighting in which the linear light form, when propagating light appears to have a larger diameter due to the aura effect. "Aura" is defined as luminous radiation. The "aura effect" is where luminous radiation appears outside of the core and cladding, and is visible in the jacket or the jacket and the space surrounding the jacket. It is when the aura effect illuminates the space surrounding the jacket that the conduit appears to have a larger diameter. A single jacket, when applied to the core and cladding has been found to provide the desired aura effect, but the effect dissipates as the thickness of the single jacket is increased. Once the jacket exceeds the useful diameter thickness, the light form does not exhibit an aura effect, and the fiber optic appears as decoupled, i.e., contained within, but separate from, the jacketing. The optic appears to be incased in the jacket with no aura effect.
However, the demand for larger diameter linear light forms is growing. At present the cost of producing thermoset cores having a diameter generally greater than 11-15 mm is cost prohibitive. Thus the need exists for increasing the apparent diameter using the aura effect in fiber-optic lighting systems.
Additionally, linear light forms, when bent past a certain degree known as permissible "bend radius", appear to have a "hot spot`. A hot spot is defined as the area of the optic that appears to be brighter than the rest of the optic. The hot spots can detract from lighting applications wherein the uniformity of the light of the light is desirable. It is thus desirable to reduce the hot spot effect.